Kamruzzaman Muhammad, Iredell Jonathan R
Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW, Australia.
Westmead Hospital, Westmead, NSW, Australia.
Front Microbiol. 2020 Jan 10;10:2934. doi: 10.3389/fmicb.2019.02934. eCollection 2019.
CRISPR-Cas (clustered regularly interspersed short palindromic repeats-CRISPR-associated protein) is a microbial adaptive immune system involved in defense against different types of mobile genetic elements. CRISPR-Cas systems are usually found in bacterial and archaeal chromosomes but have also been reported in bacteriophage genomes and in a few mega-plasmids. is an important member of the Enterobacteriaceae with which they share a huge pool of antibiotic resistance genes, mostly via plasmids. CRISPR-Cas systems have been identified in chromosomes, but relatively little is known of CRISPR-Cas in the plasmids resident in this species. In this study, we searched for CRISPR-Cas system in 699 complete plasmid sequences (>50-kb) and 217 complete chromosomal sequences of from GenBank and analyzed the CRISPR-Cas systems and CRISPR spacers found in plasmids and chromosomes. We found a putative CRISPR-Cas system in the 44 plasmids from species and GenBank search also identified the identical system in three plasmids from other Enterobacteriaceae, with CRISPR spacers targeting different plasmid and chromosome sequences. 45 of 47 plasmids with putative type IV CRISPR had IncFIB replicon and 36 of them had an additional IncHI1B replicon. All plasmids except two are very large (>200 kb) and half of them carried multiple antibiotic resistance genes including , , . To our knowledge, this is the first report of multi drug resistance plasmids from Enterobacteriaceae with their own CRISPR-Cas system and it is possible that the plasmid type IV CRISPR may depend on the chromosomal type I-E CRISPRs for their competence. Both chromosomal and plasmid CRISPRs target a large variety of plasmids from this species, further suggesting key roles in the epidemiology of large plasmids.
CRISPR-Cas（成簇规律间隔短回文重复序列- CRISPR相关蛋白）是一种微生物适应性免疫系统，参与抵御不同类型的可移动遗传元件。CRISPR-Cas系统通常存在于细菌和古细菌染色体中，但也在噬菌体基因组和一些巨型质粒中被报道过。[具体细菌名称]是肠杆菌科的重要成员，它们通过质粒共享大量抗生素抗性基因。CRISPR-Cas系统已在[具体细菌名称]染色体中被鉴定出来，但对于该物种中存在的质粒上的CRISPR-Cas了解相对较少。在本研究中，我们在来自GenBank的699个完整质粒序列（>50 kb）和217个完整染色体序列中搜索CRISPR-Cas系统，并分析了在质粒和染色体中发现的CRISPR-Cas系统及CRISPR间隔序列。我们在来自[具体细菌名称]物种的44个质粒中发现了一个假定的CRISPR-Cas系统，GenBank搜索还在来自其他肠杆菌科的三个质粒中鉴定出相同系统，其CRISPR间隔序列靶向不同的质粒和染色体序列。47个具有假定IV型CRISPR的质粒中有45个具有IncFIB复制子，其中36个还具有额外的IncHI1B复制子。除两个质粒外，所有质粒都非常大（>200 kb），并且其中一半携带多种抗生素抗性基因，包括[具体抗性基因名称]。据我们所知，这是首次报道来自肠杆菌科的具有自身CRISPR-Cas系统的多药耐药性质粒，并且IV型质粒CRISPR可能依赖于染色体I-E型CRISPR来发挥其功能。染色体和质粒CRISPR都靶向该物种的多种质粒，这进一步表明它们在大型质粒流行病学中起关键作用。
